<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    * {
        padding: 0;
        margin: 0;
    }
    
    .wrap {
        width: 300px;
        margin: 100px auto 0;
    }
    
    table {
        border-collapse: collapse;
        border-spacing: 0;
        border: 1px solid #c0c0c0;
        width: 300px;
    }
    
    th,
    td {
        border: 1px solid #d0d0d0;
        color: #404060;
        padding: 10px;
    }
    
    th {
        background-color: #09c;
        font: bold 16px "微软雅黑";
        color: #fff;
    }
    
    td {
        font: 14px "微软雅黑";
    }
    
    tbody tr {
        background-color: #f0f0f0;
    }
    
    tbody tr:hover {
        cursor: pointer;
        background-color: #fafafa;
    }
</style>

<body>
    <div class="wrap">
        <table>
            <thead>
                <tr>
                    <th>
                        <input type="checkbox" id="j_cbAll" />
                    </th>
                    <th>商品</th>
                    <th>价钱</th>
                </tr>
            </thead>
            <tbody id="j_tb">
                <tr>
                    <td>
                        <input type="checkbox" />
                    </td>
                    <td>iPhone8</td>
                    <td>8000</td>
                </tr>
                <tr>
                    <td>
                        <input type="checkbox" />
                    </td>
                    <td>iPad Pro</td>
                    <td>5000</td>
                </tr>
                <tr>
                    <td>
                        <input type="checkbox" />
                    </td>
                    <td>iPad Air</td>
                    <td>2000</td>
                </tr>
                <tr>
                    <td>
                        <input type="checkbox" />
                    </td>
                    <td>Apple Watch</td>
                    <td>2000</td>
                </tr>

            </tbody>
        </table>
    </div>
    <script>
        var j_cbAll = document.getElementById('j_cbAll');
        var j_tbs = document.getElementById('j_tb').getElementsByTagName('input');
        j_cbAll.onclick = function() {
            for (var i = 0; i < j_tbs.length; i++) {
                j_tbs[i].checked = this.checked;
            }
        }

        //2下面复选框需要全部选中 上面全选才选中
        for (var i = 0; i < j_tbs.length; i++) {
            j_tbs[i].onclick = function() {
                var flag = true;
                //每次点击下面的复选框都要循环检查4个小按钮是否全部被选中
                for (var i = 0; i < j_tbs.length; i++) {
                    if (!j_tbs[i].checked) {
                        flag = false;
                        break;
                    }
                }
                j_cbAll.checked = flag;
            }
        }
    </script>
</body>

</html>